M20 thermostat housing - throttle body heater delete

This guide will show you how to properly bypass your throttle body heater.

Parts needed

  • spare thermostat housing
  • spare throttle body plate
  • 1/4-18npt bolt or plug
  • m12x1.5 bolt
  • m14x1.5 bolt
  • 2 crush washers

Tools needed

  • drill press or hand drill
  • various drill bits
  • bench vise
  • m12x1.5 tap
  • m14x1.5 tap
  • 1/4-18npt tap
  • tap handle
  • tap magic
  • square head 8mm socket
  • ratchet
  • long flat head screwdriver
  • jb weld
  • band saw or hack saw
  • sand blaster tank or simple green / scotch bright

Thermostat housing complete from the junkyard for 10 dollars


it was super dirty

the thermostat had broken off .

So with a big flat head screwdriver pry it out.

popped off like a charm

stick the thermostat cover and the housing in a sand blaster

if not scrub them simple green and scotch bright.

well worth the effort

cut the snout for the throttle heater hose

now punch out the inner sleeve

part in a vice and about to drill it.

tap by hand

hole tapped


hole plugged

this port that has been pointed out is m12x1.5

the rest are m14x1.5

one of my holes was really gummy so i chased the thread with the tap.

make sure your tap is clean

remove your afm and stock airbox

remove your rubber intake

remove the coolant hoses on the throttle body

there are 3 torx screws on the plate going into the throttle body

pick out any crap out of the middle of the 3 torx bolts

I sawed off the tubes and then sanded the plate down and filled them with jb weld

new plate

the idea behind this was to make it look like the car was never missing anything.

and just put a bolt in the back of the block to plug that coolant port

you can spot in this picture below in a green circle

its either a m12x1.5 or a m14x1.5